Is this a behavior that persists past 5 minutes after boot?
For me, Listary latest beta does display the behavior you have mentioned for a minute or so after a reboot, then functions perfectly after that. As a rule, Listary lags the first time I all it up, takes maybe 5 seconds to register keys, and it goes back to normal behavior. I have no problems after that during day to day usage.
Must say I am loving the app thus far, and it has been a joy to use (though it has only been a month). I have no idea how I have lived without this app. Looking forward to Listary 6 release, will be purchasing the pro version then!